Many wireless communications systems require a rapid deployment of independent mobile users as well as reliable communications between user nodes. Mobile Ad Hoc Networks (MANETs) are based on self-configuring autonomous collections of mobile users who communicate with each other over wireless links having limited bandwidths. MANETs are usually temporary packet radio networks which do not involve significant, if any, supporting infrastructure. Rather than employing fixed base stations, each user node in a MANET can operate as a router for other user nodes, thus enabling expanded network coverage that can be set up quickly, at low cost, and which is highly fault tolerant.
MANETs provide critical communication services in various environments involving, for example, emergency services supporting police and fire personnel, military applications, industrial facilities and construction sites. Routing communications between two nodes in a static network generally involves simply determining the shortest route between the two nodes. However, in a MANET, the determination of an optimal communication route may involve additional factors. For example, propagation path losses, interference between users, and channel fading may require the use of an indirect route between two nodes in order to provide an acceptable Quality of Service (QoS) to the network users.
Because MANETs generally do not comprise significant supporting infrastructure, such as fixed base stations, but rely on user nodes to act as relay or intermediate nodes, participation in a MANET by a high number of users is often critical to network functionality. For example, if a MANET covers a significant area that is wider than the transmission range of any single user node, a transmission across the full width of the MANET will require relaying the transmission through at least one intermediate user node. Unless an adequate number of such intermediate, or “multi-hop”, user nodes participate in the network, and enable transmissions addressed to other nodes to be routed through the intermediate user nodes, then the network breaks down and at least some transmissions may not be completed. Conversely, as more user nodes participate in a MANET, the average distance between nodes decreases, and reliability and link quality increases.
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